Launch Pad - Perseus II Build

[Astro-Baby]

While I try and make up my mind with the fin platforms I move on to doing the fins and strakes. I had a real headache with these. The balsa was too feeble for such large fins and I had a couple of bodge up attempts using CA. I shant bore you with a litany of disasters and screw ups. I drove about 30 miles to get some basswood and they didnt have any wide enough. I built a fin from birch play and it bent badly and so forth....on and on it went....but lets look at the positives

In the end I used some balsa I had laying around and did the papered fin approach (used this years ago on a huge balsa plane - Do 335 Arrow for my eldest). I thought I could improve on the technique I used back then so I made a thick card template. Cut the balsa out using it and then used the template to whack out some thin card to the same size and shape. The fins were each given a thin layer of aliphatic and then the paper was applied. Finally each group of fins was put into a press of two books (History of the Hawker Hunter and History of the Gloster Meteor - yup I really am that geeky) with a 5kg weight on top. Turning these out too about a weeks worth of evenings spare time.

The pics are of the strakes being done like this......

 

[Astro-Baby]

Finally one the glue had dried and the fins had been well and trully pressed and were flat and true they were given a light sanding to give the edges a slight chamfer - not too much as I wanted the finished bird to ve quite hard edged - and then given a hit of CA along all edges except the root edge and left to dry overnight.

The forward fins have been marked with a red marker on their leading edges since they were cut out - the reason being is that to a casual glance they look symmetrical but they arent. The red edge is the leading edge and the tube has been marked with a note that red goes to the front in case I forget or get careless later on.

 

[Astro-Baby]

The tube was marked up (actually this was done just after the tubes were assembled together - I made up a paper template for this by wrapping a band of paper round then folding it in half and then folding it again. This would give the exact quarter points for the fins. The folds were lined in with a marker and the ring slipped over the tubes for marking up. The Zero mark '0' is so I can check the accuracy of the fin marking template itself. At zero all lines should line up i e the ones on the rocket AND the template- but they should also line up with the zero at any line (they do). I often find the fin marking templates supplied with kits to be not all that accurate so this was an attempt to remove one of the smaller gremlins.

After marking up I added the fins. My ex (under advisement from my boys) bought me a whole bunch of Estes stuff (fin alignment guide, marking up tool and cutting guides plus some hobby knives). The alighnment guide is uselss for a rockt of this size I found for the purposes of alignment but it does make a useful holder to hold stuff in position.

I didnt mount the rear cone with the engine in it for just this reason - I wanted the flat end of the tube for fin fitting rather than have the possibility of the engine assembly boattail being not quite accurate for the rocket to sit on while its fins were fitted.

Standard stuff here - thin layer of aliphatic on the fin, wait till it goes tacky, add a second layer and wham onto the rocket tube. Later they were all given a fillet of glue.

This is a departure from the instruction which have you mount the fins to the baseplates and then glue the whole assembly on. I wasnt so sure I would get a fin alighment good enough doing it that way so I am putting the fins and strakes on and then later the fin base plates will slide over the top.

 

[Astro-Baby]

With the rear fins added the boattail and motor assembly was put into the birds rear end. The extra blasa blocks I put on worked almost too well. With the interference from the glue it was a very tight fit and I had a couple of heart stoppages fitting this as it jammed on at one point in the halfway on position.

I didnt take any pics of the process but basically a ring of glue was added down the tube with a taper at the point wehere the engines top centreing ring would be - a second ring was added to the top of the tube and the whole assembly slid into place (after a few scary moments). Its worth mentioning that the boat tail really does need the CA coating. Mine would never have survived the fitting process without it.

Heres the rear assembly fitted and also a pic to give you a sense of scale of how large Perseus II is. Its againsta kitchen countertop and I imagine tins of beans are pretty much the same size everywhere.

 

[Astro-Baby]

Today...I am working on the strakes and have been since yesterday afternoon. As I like everything fully dry I find these kits take for ever - thats ok as I have lots of patience and theres no point rushing it. In the UK the weather is fould - wind and rain and we are most likley in for a few more weeks of it at least.

Heres two of the strakes being fitted....I am using an acrylic and steel ruler pegged to the tail fins to get the strakes aligned. As it happened one of the fins is off a bit which is a bit of a blow as I really wanted 100% accurate this time round.

No idea when I will post again but I will keep the build thread going.

 

[Astro-Baby]

Quick shout out......if anyone else has built the Perseus II I would be REALLY interested in knowing where the CoG should be ? She seems awfully ass end heavy with all that lumber on the tail end and she aint going to get any lighter with a pair of D12s installed.

I scaled up the CoP based on the smaller versions alleged rocksim file which seems to suggest the CoP would be at about 30" from the nose - the CoG would seem (based on the current almost finished) bird to be only slightly ahead of that by maybe 2".

Admittedly she isn't as yet carrying the recovery gear but I cant see thats going to weigh too much.

With my 'build it like a tank' mentality I am a bit worried how back end heavy she is - So far I have used almost an entire tube of wood glue on this one. Even Thunderbird with 16 fins and a load of card to make up didndt use as much glue so its certainly built (ahem, cough, cough) robustly

 

[Daddyisabar]

Old Military Aviation books make great weight and I am sure some good karma soaks into the papered balsa as well. All those TLP tail cones need a good soaking of super thin CA or finishing epoxy and will get dinged up over the rocket's flight life. If a little sin is left on the attachment point to the body tube then you will find sand paper and filler are your friends. TLP kits soak up lots glue and as long as you are not using insane amounts of glue and are building it stock with out heavier woods or glass mods then you should be OK from a stability standpoint. This is a long rocket and is more stable as a fantasy design than some of TLP's sporty scale stuff. If you are still worried then pound some modeling clay in the nose cone. Put that ring in up front to keep recovery gear from sliding down. Take your time inserting and twisting your igniters together, have good connections on a 12V launch system and the "Big P" will not let you down. They may question my lack of rocket science but as long as the good karma soaks through I should be OK.

 

[boomtube]

When I received this kit the two BT80 tubes were crunched so I replaced them with a BT80 heavy wall tube from Balsa Machining.
Then I replaced the balsa fins with basswood. Then I used a 29mm motor mount. . .Well you get the picture.
Sadly TLP doesn’t include any Center of Pressure info with their kits but I added a few ounces of lead to the nosecone on mine and it flies superbly using F and G Hobbyline motors.
As for those fin reinforcements; I enlarged the diagram included in the instructions to “Life sized” then made four copies which I glued to the balsa then cut on the lines.
Wrap some 220 sandpaper around the body tube and sand the underside of those items to fit the curve of the tube.

Currently I am working on TLP’s “Gabriel III” Anti-Ship Missile. This one I’m building stock.

 

[Astro-Baby]

Boomtube- seen your Gabriel thread - she looks a bith toi build and I can really feel for you as I have had similar (though less complex issues) with some parts on Perseus.

Heres where I got up to at the end of last weekend....all the strakes are fitted and have been given a fillet of glue.

 

[Astro-Baby]

Through the week the forward fins were added. The red ink on the front is a reminder that thats the leading edge.

As these are thinner balsa than the main fins I initially tried using a steel ruler with a 'pad' to make up the difference in thickness in order to get alignment BUT I found it just wouldnt work out. Even small imperfections in the rear fins and strakes were muliplied yup because of the distance - these forward fins are about 9" from the end of the strakes and 18" away from the rear fins. Maybe with a more solid jig it would work but I didn't have anything on hand so in the end they were aligned by eye - the rear fins were inked in red as well to help my eyeballs see where the alignment was.

All things considered it worked out well enough - at a fin per night it was Friday before all of these were set and filleted. Meantime I had been working on the main fin base parts which proved to be a bit of a pain.

Heres some pics of the forward fins and the whole bird once all the fins were on. The white band on the birds body is a templet to make sure all the fins line up in the fore/aft direction.

 

[Astro-Baby]

On Friday I had a day off work and set about the rear fin platforms. The manual says to make these up and glue the rear fins to them and then glue the whole assembly to the body tube. Reading sodmesiters thread on Gabriel I see he did just that but I was very unconvinced it would work out. Sodmesiter being a guru has skills way above mine and a good build always depends on knowing your own limits (I have high standards but low skills ) Anyway I opted to mount the fins first and then slip the fin platforms/bases over the top.

Producing these bases wasnt that hard, I do wish TLP had provided a template but it wasnt so tough to draw the template up using a high school geometry kit I picked up ages ago in a bargain shop. These, as already seen in this thread, were photocopied and glued to balsa and then cut and sanded to shape. Unfortunatel;y when these were slotted over the fins theye were found to be out of whack. Slightly too wide to one side of the fin. These parts alone took the largest part of making this kit. The first few I scrapped, the balsa was too soft for me to work with, the second set I wasnt happy with and they were made out of some obscure wood I never heard of that cut easily but was hell to sand the final set were made from basswood and I made up six of the blighters so I coulkd pick the best four later on.

Rather than do it all over again (because even my patience was getting sore tried here) I decided to cut the centre slots a bit wider to allow the platform to move off to one side and thereby have the same width of base on each side of the fin. The slight change in the angle of the base because of this looked grim to start with but a test fitting showed it was undetectable to the human eye (well mine anyway) when fitted. Rather than goi through the palava of making some more I decided to go this route. Its a bit of a bodge and I daresay I will have to answer to this at the gates of Rocket Valhalla but I really did want to move forward and not spend the rest of my life over this. (Boomtube I feel for you because of this so maybe in the great universal plan it was meant to be )

Heres the first production one being fitted - you can see the larger slot cut through it to allow it to be jiggled. The second pic is of the part fitted once the glue had dried.

A better, more precise worker than me would have done a lot better I am sure - I simply resolved never to read any Perseus II build threads in the future so I dont have to see how well this kit can be made

ps - in the final pic you can see the twin mounts for the motors are in line with one set of fins - this was quite deliberate on my part. I planned this to be that way when I put the motor assembly into the rear tube. However the join in the boattail was also lined up with the launch lugs - that was pure luck

 

[Astro-Baby]

Friday I was at this almost all day - heres a shot of another fin platform being fitted plus a picture of the now completed (from a glueing lumber to tube point of view) of the whole bird.

 

[Astro-Baby]

Next up was launch lugs - Rather than a single lug because of this bords size (and theres zip about lugs in the instructions) I decided to cut the supplied longish lug down to two smaller units and have them seperated by around 12" on the tube.

That seems to me to be a better solution and to give the bird more atability without too much stress being placed on a single lug.

 

[Astro-Baby]

The nose cone got a bit of roughging up to take off any burrs and also to rougen its finish to give the paint a grippy surface. There are only a few very shallow indents in the nose cone and I will leave those rather than fill as filling might make it worse and the bird will get some damage from flights anyway. The indents are so shallow the paint might well resolve these anyway.

 

[Astro-Baby]

Once the lugs were dry theye were given a fillet of glue - the fin bases were also given two fillets of glue and left to dry. Currently I am in the filling and sanding phase to cover the gaps around the fins caused by my shoddy workmanship (should that be workwomanship ) and also to give the bases a solid line to the body tube.

To keep weight down I did consider making a paper pattern that would hang down from the base to the body tube but a few attempots resulted in not much fun, lots of mess and a not appealing finish hence the filler. I am using a fairly light flexible filler for this which has worked well on other stuff.

Its going to be a lot of filling and sanding for a week or so.

 

[Astro-Baby]

Was just having some chill time and it occurred to me that some of this thread may seem negative to TLP - I cant speak for the rest of their stuff but I am not unmhappy with Perseus II or the product overall - its very much a builders kit and its not for the faint of hear for sure. It does require a lot of input from the builder.

I dont think thats a negative really - its been challenging to build but its pretty clearly stated on their kits that they are not for the novice and thats what I buight it for - a challenge and the joy of construction. AT times its been a bit testing but I have been enjoying the build.

So theres no nagativity aimed at TLP on this - my only real gripe has been I wish they had included a template for the fin bases - it would have cost so little but helped so much.

 

[sodmeister]

Superb.......absolutely beautiful !

I do indeed need to get one of these into my collection ,one of the very few I do not have, a handsome looking piece of ordnance I must say.

As for your platforms, I doubt there is an easy way of tackling them ,very tedious work to say the least ,but you`ve done a fine job on them !!

Another way for a lazy person (myself) would be to adhere the side fin parts first and fill in with smaller bits.......but that might be heresy ,so best be done your way LOL

I agree ,these kits are not for the faint of heart ,and more of a stepping stone for the builder to add as much or as little detail to the kit and to aquire new building skills and perhaps do a little thinking outside the box......kind of like the old days of building rocket kits !!

I remember when I was finally able to aquire these kits via online vendors (there were very very few and the kits very limited in production) it was a gateway to new building adventures and of subjects I loved.

Keep up the great work of this enjoyable build thread !!!!!

Sincerely;

Paul T

 

[rocketgeek101]

Outstanding build! Your attention to detail is fantastic. That sure is a nice looking bird.

 

[NJRick]

Astro...you are doing a GREAT job with this build! Can't wait to see it done and painted!

 

[Astro-Baby]

Thanks guys, Paul thats high praise indeed from you as your birds are always the bomb. Your Gabriel just made me weep as its so damn pretty.

My facilities are so limited I can only aspire to great work ( as opposed to actually acheive it ! ).

I did consider a few mods. Some small antennae on the rear of the fins, if it was a surface go air it would probably have some guidance, i was also going to some paper rectangles to the rear of the bird to give it some detail. These would be like thinner versions of the very flat strakes on a Sea Dart but I found the one I made up didnt loom right. The angles on the fin bases always made the back end look a bit cluttered or not true.

I also consired some thin strakes at the top end just after the nose cone to add a bit of strength to the front end. I may add those for nose weight later. On the whole I think the finish will be just as perthe box art.

Any ideas on whether a 12v launcher is really needed with twin motors or whether a 9 bolt will be enough ? Dont really want to have to buy a 12v launcher if I dont have to.

 

[sodmeister]

I`ve seen your builds ,no need to aspire ,you are there !

I`m not sure about the 9 volt battery question ,as all I (we) use are 12 volt high amp. deep cycle batteries for most of our motors,be it low or high power......and it`s all I use for my BP clusters along with those lovely Quest igniters.

Now of course ,I do have that small 9 volt remote launch controller from Apogee and it works fine for electric matches and the Quest igniters also (have not tried it on the stock Estes ones ,although I never use them )

So a 9 volt system may fire a cluster of BP motors using the Quest igniters (pretty sure as they require very little power to ignite) not sure however about the Estes type.


Cheers


Paul t

 

[gdjsky01]

If you would be so kind as communicate to me the fin dimensions and placement from the rear of the rocket and the tube length. I'd be happy to plug them into rocksim and give you a CP. Then you can adjust the CG as need be.

I have the Perseus II but alas it's still in the build queue whilst I get started on my Matra Magic R.550.
- Jeff

 

[Astro-Baby]

Hi - I will get dimensions out to you in a few days....been a long day today at work and am really tired out.

Mel

 

[gdjsky01]

Of course. Take your time. :wink: I am off this week 'in-between' switching employers.

 

[aditat2]

I have one of these fine birds in primer at the present. Yes, TLP kits take some time and are not for beginners. That's exactly why I love them. Great job on your build so far. How are you going to paint it? I am going with typical Navy type colors to keep it somewhat true to type, but since there are no photos of this missile that I could find, you're pretty much on your own. It was only a prototype after all.

 

[TopRamen]

Lookin' good! Can't wait to see how you finish her off.

 

[Astro-Baby]

I am spinning round in circles on finish. I thought kf doing it a muted red with white bands or maybe a dove grey overall with a white nose cone and some black bands but I will peobably wimp out and do it as per the box artwork of white with some black markings just to keep the paint simple. Naval missiles always seem to be white for some reason or at least a slightly off white.

I havent hac any time to work on it so far this week but Thursday night my kids are out and so is my partner so I will have some quiet time to do a bit of sanding.

 

[Astro-Baby]

Thought as I have a quiet night I would post an update.

The rear end has had a hit of filler and then sanded down. Its still looking a bit rough so another hit of filler will goon this weekend and then some more sanding. The rear fin platforms have been shaped up. They look a bit roug in these pics but look better in real life.

gdjsky01 worked out the CP for me (thanks muchly for that) and a weighing in session with a pair of D12s suggests the CG is perilously close to the CP with perhaps only an inch of difference - eek - weighing this missile scares me everytime I do it so I am going to wait till she is finished with coats of paint and see where the CP/CG is after that.

With the UK weather being rain, rain and rain and very cold I cant paint right now anyway - I may try and get a primer on and hope for a few sunny winter days to get the final coats on later on.

As I cant work on the rocket itself I decided to start another project - my own launch controller. Its dubbed CRM-114 and movie buffs will spot the connection I am sure I will post up on that in the Ground Support forum. Like everything I do its waaaay over engineered but I do this for fun not for profit (thankfully !!!).

Chairman Mao may have said a journey of a thousand miles starts with a single step but I would say a journey to emptying the bank balance starts with a single hobby Comrade

 

[Astro-Baby]

Heres an update on how the build is going (slow) so far....

gdjsky was kind enough to use rocksim to calculate the CP for me and it seemed to accord with my own inexpert calculations quite closely. In a nut shell all that filler and extra balsa on the back end means the CG is very close to the CP (To be honest even without that extra filler and balsa I suspect this bird may be a bit tail end heavy).

I have decided to hold fire on adding weight until the bird is completed with paint and the parachute harness etc BUT I thought deadweight would be...well...deadweight. Why not improve the bird rather than just add weight to its nose ?????? One of the weaknesses of this bird was apparent at the start but it became a real liability during painting which is the front end of the tube is very thin paper and its also quite long. It made for a permament risk that when handling the bird with its nosecome removed that the front end of the tube could crumple and bend easily. I resolved to use some of the extra noseweight needed to do something about that. The very edge of the tube has been given some hits of CA and down inside I used some thick card stock, glued some aluminium foil to it and then ran it inside the tube to give the front end a bit more rigidity. It kind of worked - not as strong as I would like but I am somewhat happier.

 

[Astro-Baby]

FInally with the lauch controller finished I had to go back to the salt mines of sanding and finishing. Its picth black here at night and so I have to wait for weekends when I have good daylight to do the finishing work.

The rear end has had filler, sanding, filler, sanding, filler and sanding and so on. Its been a chore but with the last primer I think I am now there. The fins are very thick and chunky and I wanted them to be blunt edged rather than sanded to and edge. Becaise of the thickness the edges needed a bit of filling and sanding to the the bird to look sharp.

These pics were done after the first primer coat and with sanding and refinishing in progress.